C :

#include <stdio.h>
void fun(int n)
{
	if(n==0)
		return;
	else
	{
		fun(n/8);
		printf("%d",n%8);
	}
}

main()
{
	int n;
		scanf("%d",&n);
		fun(n);
		
}

C++ :

#include<iostream>
#include<cstdio>
#define size 100
using namespace std;
int a[size+1],n,d,i=0,j;
int main()
{
	cin>>n;
	//cin>>d;
	d=8;
	do{
		a[++i]=n%d;
		n/=d;
	}while(n!=0);
	for(j=i;j>=1;--j)
	cout<<a[j];
	return 0;
}

Pascal :

program qi26760;
var
 a:array[1..100]of longint;
 i,j,k,n:longint;
begin
 readln(n);
  i:=0;
 while n<>0 do
  begin
   i:=i+1;
   j:=n mod 8;
   a[i]:=j;
   n:=n div 8;
  end;
for k:= i downto 1 do
 write(a[k]);
end.